Low frictional drag coated paper products and method of preparation thereof



Jan. 14, 1958 D. G. EDWARDS ET AL 2,819,986

LOW FRICTIONAL DRAG COATED PAPER PRODUCTS AND METHOD OF PREPARATIONTHEREOF Filed July 26, 1954 MELVIN C EDLUND A TTORNEYS INVENTOR. DAV/DG. EDWARDS LOW FRICTIONAL DRAG CQATED PAPER PROD- UCTS AND METHOD OFPREPARATION THERE- 0F Application .iuly 26, 1954, Serial No. 445,726

5 Claims. (Cl. 117-92) This invention relatesto the reduction offrictional resistance between coated paper products and surfaces incontact therewith, and more particularly to the formation of a film ofdrag reducing agent on the surface of paper products having protectiveor decorative coatings of wax or the like.

Coated paper products are extensively employed for wrapping andpackaging numerous articles. Usually the setting up of paperboardcontainers, and the wrapping or packaging of articles is accomplished bymeans of automatic machinery. Although paper products coated withunmodified low melting paraffin waxes generally have a sufficiently lowfrictional drag to be readily handled .by such machinery, the lowmelting unmodified waxes have undesirable properties, such as a greasyfeeling, a tendency to seal to adjacent wax surfaces in hot weather,anda limited resistance to penetration by grease. The high melting pointunmodified waxes, and the improved modified wax coatings which containadditives overcome the disadvantages of the low melting parafiin waxes.However, such high melting point unmodified waxes and also the modifiedwax compositions have a relatively high amount of frictional resistancewhich renders paper products coated with such compositions difiicult toseparate from stacks of similar paper products by sliding motion whenindividual sheets in the stack are fed successively to equipment by theusual paper stack feeding devices, causes scufiing of the wax coating,and reduces the efficiency of the machinery as the coated paperproductspass through the various setting up or packaging operations. Attempts tosolve this frictional drag problem by modifying the coating compositionhave not been entirely successful since other desirable properties ofthe coating have usually been adversely affected or the economic aspectshave been made such modifications unfeasible.

To summarize this invention, it comprises the reduction of thefrictional surface resistance of coated paper products or the likewithout affecting the advantageous properties of the coatings byapplyinga .thin film of a drag reducing agent to the surface ofsuch coatedproducts, which film remains on such surface as a discrete lubricatinglayer. The drag reducing agent may be any liquid compound that has thephysical .property .of reducing frictional drag and in this connection,.the liquid may be of relatively low viscosity or it may have theconsistency of a relatively thick gel. The numerous compounds that havethe property of reducing frictional resistance of coated paper productsare readily deter mined by a simple comparison of frictionalsurfaceresistance of coated paper products with and without a film ofthe compoundapplied thereto, as indicatedbythe feel .of the-specimens,or by frictional measurements.

Although the drag reducing agentmay be applied directly to the coatedpaperproductin undiluted form,

namely, .withoutra solvent ,or ,other lcarrierlagent, best results areobtained by incorporating the drag reducing atent ICC agent in avolatile liquid carrier, such as water, to form a liquid compositionthat may be either a solution or an emulsion. The volatile liquidcarrier evaporates after the mixture is placed on the coated paperproduct leaving a thin discrete film-of drag reducing agent on thesurface of the coating. A surface active agent is desirably included inthe mixture'to -provide improved wetting of the mixture'on the coated'paper product, and to provide a stable-emulsion when'the drag reducingagent employedis insoluble in the volatile liquid carrier.

Compounds that maybe employed as drag reducing agents areorganic=compoundshavingthe following properties: a-viscositywhich may'varyfrom a low viscosity liquid to a=viscous semi-liquid substancehaving the consistency of a gel; o low --solubility in the coating ofthe paper product; 't'he'property of forming a film on the surface ofthe coating; the property of being softer than the coating so thattheytlo not become embedded in the coating. Also, drag-reducing agentsgenerally should be non-volatile so that thefilm of drag reducing agentwill remain on the coating in storage until the wrapping or packagingoperations have been completed.

By applying'thefilm of drag reducing agent to coated paper products inaccordance with this invention, the frictional resistance betweenacoated paper product and surfaces in contact therewith is reduced tothe point where frictional drag is no'longer a problem, and sending ofthe coated surface is reduced. Furthermore, this lowered frictionalresistance 'is'obtainedwithout affecting the remaining desirableproperties 'ofthe paper coating. This inventionmaybe employed with greatadvantage in reducing the frictional resistance ofpaperboard products,such ascarton blanks, that'havegcoatings of wax or modified waxcompositions, both hereinafter generally designated as waxcoatings. -Itmay be employed with particular advantage when such wax coatings areapplied in a cold water -waxer. By merely incorporating a dragreducingagent in the -cold water bath of the cold waxer, a filmo'f adragreducing agent is formed on the surface of the wax coating withoutthe necessity of making alterations in existing equipment.

The accompanying drawing is a schematic sectional side elevation ofa-conventional cold waxer for paperboard products embodying a cold waterbath in which the drag reducing agent of this invention mayadvantageously be incorporated. ,It is to be understood that theelements of the coldwaxer are not shown in proportion to their actualrelativesizes, but are drawn for purposes of illustration only.

In greater detail,:the uncoated paperboard carton blanks 2 are stacked'edgewise and inclined relative to inclined support table -3. Theusualdam 'or choke member 4 is provided adjacent-the 'dischargeend oftable 3 so as to insure that only thesingle outermost sheet or blank isfed at a time. A-continuously rotatingrubber covered feed roll 6 isprovided adjacent choked, and the feed roll is driven-in acounter-clockwise direction with reference to the drawingto effectfeeding of the respective carton blanks 2 onto acontinuouslymovingendless conveyor '7 mounted on'conveyor rolls 8. Support rollers 9support the central part of conveyor '7, and retainer rollers 11serve-to maintaintheblanks 2 on the conveyor surface.

The blanks 2 are carriedby conveyor 7 to conventional felt covered wax,applicator rolls 12 where hot liquidwax is'applied. The upper'applicatorrolls'have hot wax applied to their-surfacesby'means of pipes '13 havingnozzles 14 disposed therein'for spraying wax. The lowerapplicatorgrollshavetheir lowermost portionsdisposed in hot molteniwaxcontainedinatray16,=and..ca1'ry wax to the blanks as the applicator.rolls -rotate. In this .:manner, molten wax isappliedto both thetopand.bottomsurfaces of carbon blanks 2. The carton blanks 2 are conveyed bythe rotation of the applicator rolls 12 to finishing rolls 17 where theexcess wax is removed.

After the carton blanks 2 have been soaked with molten wax and passedthrough the finishing rolls, the blanks are plunged into the usual coldwater bath 18 where the wax is solidified to form a coating on thecarton blank; the water in the bath being usually continuouslycirculated at a temperature of about 40 F. The cold water bath 18 iscontained in any suitable tank 19, and the water temperature ismaintained by circulating the water in the cold Water tank through pipe21 into a coil cooled refrigerating tank 22 and back into the cold watertank 19 through pipe 23 by means of pump 24. The wax coated blanks 2 areconveyed through the cold water bath by upper and lower conveyor belts26. After the wax coated blanks 2 have passed through the water bath andthe wax coating has solidified, the excess water is removed from the waxcoated blank surfaces by passing such blanks through wringer rolls 27.The wax coated blanks are removed by discharge conveyor belt 28.

By incorporating a drag reducing agent in the cold Water bath of thecold waxer, a thin film of the drag reducing agent is produced on thesurface of the wax coating as water is absorbed into the paperboardblank or evaporates. No changes need be made in existing equipment, andno additional steps need be performed when the drag reducing agent isadded in this manner. Furthermore, the wringer rolls 27 automaticallyremove any excess of drag reducing agent appearing on the surface of thecoated paper products, and a desirably thin film of the drag reducingagent is produced. In this connection, the moving conveyor belts 26 mayserve as the means for forming an emulsion or mixing the solution of thedrag reducing agent in the water.

Compounds suitable for use as drag reducing agents may readily beselected from the numerous available organic liquid compounds by asimple comparison in the feel of two specimens of coated paperboardrubbed together before, and after application of the drag reducingagent. If desired, the effectiveness of a compound as a drag reducingagent may be evaluated more quantitatively and with greater accuracy byemploying a standard force to pull a standard size specimen of a coatedpaper product from between two similar pieces of the coated paperproduct under a constant pressure. The time re quired to withdraw thecentral specimen is an indication of the frictional resistance of thecoating for the paperboard product. A comparison of the times forwithdrawing such coated paperboard specimens before and after they arecoated with a drag reducing agent readily illustrates the efficacy ofthe compound for lowering the surface frictional resistance of coatedpaper products.

The data in the following table effectively illustrates, for a few ofthe many drag reducing agents tested, the reduction in the surfacefrictional resistance of coated paper products obtained by employing adrag reducing agent in accordance with this invention. Samples ofpaperboard /2 in. long and 1% in. wide coated with a modified waxcomposition containing 3% by weight poly ethylene and 5%microcrystalline parafiin wax combined with 92% by weight paraffin waxhaving a melting point range of 143 F. to 150 F. (A. M. P.) wereemployed for the tests. Three of such specimens interleaved for 5 inchesalong their lengths were placed on a horizontal flat surface andsubjected to a normal force of 1500 gms. applied to one square inch ofthe surface of the top specimen. The middle specimen was pulled frombetween the other similar specimens by subjecting it to an average forcedirected along its lengthwise horizontal axis of 1.68 lbs, and the timeto completely withdraw the middle specimen was measured. In these tests,the indicated percent by weight of drag reducing agent was dissolved oremulsified in water as a carrier. One percent by weight, based upon theweight ofdrag reducing agent, of

polyoxyethylene sorbitan monoleate, a surface active agent sold by AtlasPowder Company under the name Tween 80, was employed in all cases, andit served as an emulsifying agent for drag reducing agents insoluble inwater. In other words, 0.03% by weight of the surface active agent basedupon the total weight of drag reducing agent, volatile liquid carrierand surface active agent was employed in the tests; except 0.06% byweight surface active agent based upon the total weight of thecomposition was employed in the test in which 6% drag reducing agent wasused. The emulsions or solutions of the drag reducing agents weresponged on the surface of paperboard coated with the modified parafilnwax coating and the specimens were allowed to dry overnight at roomtemperature before the tests were made.

TABLE Comparison of frictional surface resistance of coated paperboardwith and without a film of drag reducing agent Percent by Weight of DragReducing gt. in Carrier Average Removal Time (Secsl Drag Reducing Agentwwc The foregoing table illustrates the appreciable lowering of thefrictional surface resistance obtained by employment of a drag reducingagent in accordance with this invention. Also, the tests illustrate asimple manner of determining the efiicacy of a compound as a dragreducing agent. Similar tests on paperboard coated with unmodifiedparafiin wax having the relatively low melting point range of between133 and 135 F. (A. M. P.) gave a withdrawal time of 11 seconds withoutuse of a drag reducing agent. Since the time for the modified waxcoating was 226 seconds, the importance of employing a drag reducingagent in accordance with this invention is readily apparent.

The numerous drag reducing agents that have the property of reducing thefrictional surface resistance of coated paper products have other commoncharacteristics. They are all organic compounds with a viscosity whichmay vary from a low viscosity liquid to a viscous gel. In morequantitative terms, the viscosity of the drag reducing agent may varyfrom less than one centipoise up to 10,000 centipoises, or in otherwords, have a viscosity below 10,000 centipoises.

The solubility of the drag reducing agent in the coating is anotherfactor in determining the usefulness of a compound for reducing thesurface friction of coated paper products. If a compound is soluble toany substantial extent in the protective coating, it tends to lose itsidentity as a separate discrete film, and its function in loweringfrictional surface resistance is impaired. Solubility of the coating inthe lubricant, or lubricant in the coating, should be less than /2% byweight for best results. Solubilities of waxes in organic liquids mayreadily be determined experimentally or obtained from availableliterature, such as the book entitled Commercial Waxes," by H. Bennett,Chemical Publishing Company, Brooklyn, New York. Deodorized kerosene isan example of a liquid organic compound that is too soluble to serve asa drag reducing agent for an essentially wax coating.

In addition, suitable drag reducing agents have the property of forminga film on the surface of the coated paperboard although the film neednot be absolutely continuous in order to perform its function. In otherwords, the compound employed as a drag reducing agent should wet thesurface of the coated paperboard. Usually, compounds that have a contactangle with the coated surface of less than 103 are satisfactory. Theangle is measured from the inside of the film to the tangent of the filmwhere it intersects the coating.

Furthermore, the drag reducing agent should be softer than the coatingto which it is applied so that the agent does not become embedded in thecoating and increase the frictional resistance. This property ofsoftness is usually inherently present if the drag reducing agent hasthe other properties specified.

The drag reducing agent is generally applied to the coated paper productlong before the product is to be employed for wrapping or packagingvarious articles. Consequently, the drag reducing agent should berelatively non-volatile so that it will remain on the surface of thecoating and not evaporate. The vapor pressure of a compound divided bythe square root of its molecular weight provides a measure of thevolatility of a compound. For the purposes of this invention, it is notusually desirable to employ a compound as a drag reduc ing agent if theratio of the upper vapor pressure in millimeters of mercury to thesquare root of its molecular weight is greater than 0.1. For example,Cellosolve (2- ethoxyethanol) sold by Carbide and Carbon Chemicals Co.is too volatile to be employed as a drag reducing agent for mostpurposes, and the ratio of the vapor pressure in millimeters of mercuryto the square root of the molecular weight is about 1. However, when thedrag reducing agent is applied shortly before the coated paper productis to be employed, volatility of the drag reducing agent is not such acritical factor as long as the film has not completely evaporated.

In the course of numerous tests on drag reducing agents, an additionalempirical factor has been discovered that provides an indication of thesuitability of an organic compound as a drag reducing agent. It has beenfound that for all drag reducing agents, the product of the viscosity(in centipoises) by the molecular weight of a compound is between about10,000 and 1,000,000. When the compound is very viscous at roomtemperatures, the viscosity of the compound at its melting point wasemployed in arriving at this result. Consequently, although the feel ordrag time of a specimen having a film of drag reducing agent, comparedto the feel or drag time of a coated specimen without a drag reducingagent, is the easiest method of determining the efficacy of a compoundas a drag reducing agent, the foregoing physical properties may also beemployed to select a drag reducing agent.

Examples of a few of the preferred drag reducing agents that mayadvantageously be applied to paperboard coated with wax or modified waxcoatings are polyoxyethylene glycols sold by Carbide and CarbonChemicals Co. as Carbowax 1500 (average molecular weight 500-600),Polyethylene Glycol 300 (average molecular weight 285315) andiolyethylene Glycol 600 (average molecular weight 570-630); glycerine;mineral oil; vegetable or animal shortening; cottonseed oil; vegetablefat; and castor oil. If the coated paper product is to be used forWrapping food, non-toxic drag reducing agents, such as polyoxyethyleneglycols, should be employed.

The thin film of drag reducing agent is most advantageously applied tocoated paper products by incorporating the drag reducing agent in avolatile liquid carrier and applying the mixture of drag reducing agentand carrier to the surface of the coated paper product. However, it

is not essential that the drag reducing agent be incorporated in avolatile carrier since the pure undiluted agent may be applied to thecoated paperboard. The volatile carrier evaporates and leaves a thinalmost imperceptible film of drag reducing agent on the coating of thepaperboard.

Any volatile carrier for the drag reducing agent may be employed as longas it does not stain the paper product or dissolve the coating on theproduct. Water is the most practical volatile carrier since it is themost inexpensive and it does not harm the paper or coatings for thepaper. Consequently, water soluble drag reducing agents are easier toemploy with water as the volatile liquid carrier than agents insolublein water, since insoluble agents must be emulsified. However, othervolatile carriers including hydrocarbons such as benzene and Xylene,halogenated hydrocarbons such as trichlorethylene, alcohols such asethyl alcohol, and ketones such as methyl ethyl ketone may be employedif the coating of the paper product is not affected by the carrier.

It is usually desirable to incorporate a surface active agent in themixture of drag reducing agent and volatile liquid carrier. The surfaceactive agent improves the wettability of the mixture on the coated paperproduct, and provides improved retention of the film on the coating.Furthermore, when water is employed as the carrier and the drag reducingagent is insoluble in Water, the surface active agent generally acts asan emulsifying agent to maintain the drag reducing agent dispersedthroughout the carrier. Surface active agents of nonionic, anionic, andcationic character have proven to be satisfactory for the purposes ofthis invention.

Examples of suitable surface active agents are polyoxyethylene sorbitanmonoleate, a non-ionic compound, sold by Atlas Power Company under thename Tween N-soya N-ethyl morpholinium ethosulfate, a cationic surfaceactive agent, sold by Atlas Power Company under the name 6-271; andnaphthalene sulfonic acid condensate, an anionic surface active agentsold by Antara Chemicals as Blancol; as well as any of the other wellknown surface active agents.

When a high proportion of a water insoluble drag reducing agent isemployed, it is sometimes necessary to employ a surface active agentthat is particularly effective in maintaining a stable emulsion. Apolyoxyethylated fatty acid sold by Antara Chemicals under the nameEmulfor VN-430 has proven to be effective in maintaining an emulsion,eitherwhen used alone or together with another surface active agent.

The proportional amount of drag reducing agent that may beadvantageously employed to form a film on the surface of a coated paperproduct may vary from a fraction of a percent to one hundred percent byweight of the total weight of the drag reducing composition applied tothe coating. Even a fraction of a percent of drag reducing agentincorporated in a volatile carrier serves to provide some improvement.However, best results in reducing frictional surface resistance ofcoated paper products as indicated by quantitative tests are obtainedwhen the drag reducing agent comprises from 1% to 20% by weight of themixture of drag reducing agent and carrier. The amount of volatileliquid carrier employed may accordingly vary from zero to over 99% byweight of the mixture. Best results are obtained by employing 80% to 99%by weight of carrier and from 1% to 20% by weight drag reducing agent ina composition of drag reducing agent and volatile liquid carrier.

Although it is not essential that a surface active agent be employedunless it is required to form an emulsion of a drag reducing agent thatis insoluble in the volatile liquid carrier, a surface active agent ispreferably in cluded in the mixture of drag reducing agent and volatileliquid carrier for the reasons previously enumerated. Therefore, theamount of surface active agent may vary from zero to about by weight ofthe drag reducing agent, or in other words, from zero to about 2% byweight of the composition of volatile liquid carrier, drag reducingagent and surface active agent. The preferred amount of surface activeagent is about 0.25% to 2.5% by weight based upon the weight of dragreducing agent. In other words, when a surface active agent is employed,the preferred range of the components of the composition base upon theweight of the entire composition is from 1% to by Weight drag reducingagent, 79.5% to almost 99% by weight volatile liquid carrier, and 0.0025to 0.5% by weight surface active agent.

The preparation of a mixture of drag reducing agent, volatile liquidcarrier and surface active agent does not present any particular problemregardless of whether or not the surface active agent is soluble in thevolatile liquid carrier. Either an emulsion or a solution is readilyprepared by vigorously mixing the components of the mixture.

The drag reducing agent or mixture of drag reducing agent, volatileliquid carrier and surface active agent may readily be applied to thecoated paper product by dipping, by spraying, or by brushing the coatedpaper product in the drag reducing agent or mixture. Best results havebeen obtained, as previously related in greater detail, by incorporatingthe drag reducing agent and surface active agent in the cold water bathof the cold water waxer.

After the mixture of drag reducing agent, volatile carrier and surfaceactive agent has been applied to the coated paper product, the volatilecarrier evaporates leaving a discrete film of drag reducing agent on thesurface of the coating, although this film need not be continuous overthe entire coated surface of the paper. The desired film of dragreducing agent is very thin, and is almost imperceptible on the coatedpaper product. However, a comparison of the feel of the coated paperproduct with and without the film of drag reducing agent readily revealsthe presence of the drag reducing agent due to the comparativelyslippery feel when the film of the agent is present.

The amount of drag reducing agent required for forming a film on coatedpaperboard varies with the particular drag reducing agent employed andwith the proportion of drag reducing agent mixed with the volatileliquid carrier. With an aqueous solution containing 2%% by weightpolyoxyethylene glycols (average molecular weight 500-600), sold byCarbide and Carbon Chemicals Co. under the name Carbowax 1500, lb. ofthe Carbowax 1500 drag reducing agent was consumed on 1000 square feetof coated paperboard surface measuring the area on both sides of thepaperboard, or 500 square feet of paperboard as conventionally measuredon one side of the paperboard.

The drag reducing composition is maintained by adding amounts of make upsolution mixed in the same proportion as the original composition torestore the original volume. The solutions or emulsions of drag reducingagent volatile liquid carrier and surface active agent are substantiallyuniform and the proportions of the components remain about the same asthe paperboard carton blanks use up the drag reducing composition.

Although the film of drag reducing agent of this invention isparticularly applicable to paper products having protective ordecorative coatings of wax, a drag reducing agent may also beadvantageously employed on other coatings for paper products, such asvinyl acetate coatings.

The following are typical working examples of the preparation ofmixtures of drag reducing agent, volatile liquid carrier and surfaceactive agent for application of a film of drag reducing agent inaccordance-with this invention. In all examples, the mixture-was appliedas the paper product passed through the cold water bath of the coldwaxer.

EXAMPLE 1 350 lbs.

The polyoxyethylene glycol drag reducing agent was dissolved togetherwith the surface active agent in 40 gallons of water at C. in a steamjacketed stainless steel mixing tank with mixing for 30 minutes. Theresultant mixture was added to the remaining 1840 gallons of watermaintained by a refrigerating unit at about 40 F. in the cold water bathsystem of the cold water waxer of the type illustrated in theaccompanying drawing. The cold waxing machine was allowed to run for onehour with the conveyor belts in motion in the cold water bath to providecomplete mixing before sending paperboard blanks through the cold waxer.

Paperboard carton blanks were then sent through the cold waxer wherethey obtained a coating of modified wax comprising 3% by weightpolyethylene and 5% microcrystalline paraffin wax combined with 92% byweight of paraflin wax having a melting point range of 143 F. to F. (A.M. P.). A thin film of drag reducing agent was formed on the modifiedwax coating. 4 lb. of the Carbowax 1500" drag reducing agent wasconsumed on each 1000 square feet of paperboard carton surface passedthrough the cold Water bath.

The resultant individual blanks were readily separated from a stack ofblanks and set up by automatic carton setting up machinery withoutchattering or loss of efliciency because of frictional drag.

EXAMPLE 2 Paperboard carton blanks were passed through the cold waterbath of the cold water waxer containing the above mixture. A thin filmof drag reducing agent formed on the surface of the wax coating whichgreatly reduced the frictional resistance of the wax coated surfaceapplied to the blanks, and enabled the blanks to be readily set up byautomatic carton setting up machinery.

EXAMPLE 3 A mixture of the following components was prepared:

Amount Shortening, a hydrogenated cottonseed oil, sold by Swift andCompany (drag reducing agent) Polyoxyethyleue sorbitan monoleate(surface active agent) sold by Atlas Powder Company as Tween 80 4.7lbs.Water (volatile liquid carrier).. 15,600 lbs. (1880;.

- gallons).

468 lbs.

The shortening was melted in a jacketed stainless steel kettle, andone-half (2.35 lbs.) of the surface active agent was stirred into themelted shortening. The other one-half (2.35 lbs.) of the surface activeagent wax mixed with 125 gallons of water maintained at a temperature of130 F. The hot water solution of the drag reducing agent was then addedto the melted shortening while agitating vigorously. The agitation wascontinued until the temperature of the mixture was 30 C. (about C. belowthe melting point of the shortening). The mixture was then placed in theremaining 1755 gallons of water in the cold water bath of the cold waterwaxer. 1880 gallons of water was the normal capacity of the cold watersystem, including the refrigerating unit and the cold water tank of thecommercially employed cold water waxer in which the drag reducingcompositions of the examples were applied. However, varying amounts andproportions of volatile liquid carrier and the other components may beemployed as previously related.

Carton blanks were then waxed in the cold waxer with an unmodified highmelting parafiin wax (l60165 F. A. M. P.). The film of the shorteningdrag reducing agent was applied to the wax coated blanks as they passedthrough the cold water bath containing the drag reducing agent mixture.The resultant coated carton blanks had a low frictional resistance tosliding movement.

We claim:

1. The method of reducing frictional resistance between a surface and anadjacent sheeted paper blank having a water insoluble substantiallysolid protective coating composed primarily of wax in order to enhancerelative movement between said surface and said coating and to protectsaid coating against scufiing, which consists essentially in forming onsuch coating of said paper blank a film of a lubricating agent byapplying to said coating an organic liquid compound which is essentiallyinsoluble in and softer than said coating and which is substantiallynon-volatile, and retaining said organic liquid lubricating agent as adiscrete film on such coating to provide reduced frictional resistanceto movement between contacting areas of such coated paper blank and toreduce chattering and frictional resistance between said coated paperblank and machinery for handling such paper blank.

2. The method of reducing frictional resistance between a surface and anadjacent sheeted paper blank having a water insoluble substantiallysolid protective coating composed primarily of wax in order to enhancerelative movement between said surface and said coating and to protectsaid coating against scuffing, which consists essentially in forming onsuch coating of said paper blank a film of a lubricating agent byapplying to said coating a mixture comprising a volatile liquid carrierthat is insoluble in said coating, and a substantially nonvolatileorganic liquid compound which is essentially insoluble in and softerthan said coating, and retaining said organic liquid compound as adiscrete film on such coating upon evaporation of said volatile liquidcarrier, said retained film of such organic liquid compound providingreduced frictional resistance to movement between contacting areas ofsuch coated paper blank and reducing chattering and frictionalresistance between said coated paper blank and machinery for handlingsuch paper blank.

3. The method of claim 2 in which the organic liquid compound is solublein said volatile liquid carrier.

4. The method of claim 2 in which the mixture of volatile liquid carrierand organic liquid compound is an emulsion.

5. In the formation of a paperboard carton by setting up with automaticmachinery a paperboard carton blank having a water insolublesubstantially solid protective coating composed primarily of wax, themethod of reducing frictional resistance between the paperboard cartonblank and adjacent blanks in removing said blank from a stack of blanksand of reducing chattering and frictional resistance between said coatedcarton blank and the carton setting up machinery, which consistsessentially in forming on such coating of said carton blank a film of alubricating agent by applying to said coating a composition comprising79.5% to almost 99% by weight of water, up to 0.5% by weight surfaceactive agent, and 1% to 20% by Weight based on the total weight of thecomposition of a substantially non-volatile organic liquid compoundwhich is essentially insoluble in and softer than said coating, andretaining said organic liquid compound as a discrete lubricating film onsuch coating upon evaporation of said water.

References Cited in the file of this patent UNITED STATES PATENTS Re.17,605 Schecker Feb. 25, 1938 1,688,478 Weiss Oct. 23, 1928 1,769,633Fischer July 1, 1930 1,839,868 Damarin Jan. 5, 1932 2,017,449 ThompsonOct. 15, 1935 2,167,711 Dalton Aug. 1, 1939 2,642,366 Rumberger -1 June16, 1953 OTHER REFERENCES Synthetic Organic Chemicals, 12th ed., 1947,Carbide and Carbon Chemicals Corp., New York, N. Y., page 21. (Copy inDiv. 25.)

1. THE METHOD OF REDUCING FRICTIONAL RESISTANCE BETWEEN A SURFACE AND ANADJACENT SHEETED PAPER BLANK HAVING A WATER INSOLUBLE SUBSTANTIALLYSOLID PROTECTIVE COATING COMPOSED PRIMARILY OF WAX IN ORDER TO ENHANCERELATIVE MOVEMENT BETWEEN SAID SURFACE AND SAID COATING AND TO PROTECTSAID COATING AGAINST SCUFFING, WHICH CONSISTS ESSENTIALLY IN FORMING ONSUCH COATING OF SAID PAPER BLANK A FILM OF A LUBRICATING AGENT BYAPPLYING TO SAID COATING AN ORGANIC LIQUID COMPOUND WHICH IS ESSENTIALLYINSOLUBLE IN AND SOFTER THAN SAID COATING AND WHICH IS SUBSTANTIALLYNON-VOLATILE, AND RETAINING SAID ORGANIC LIQUID LUBRICATING AGENT AS ADISCRETE FILM ON SUCH COATING TO PROVIDE REDUCED FRICTIONAL RESISTANCETO MOVEMENT BETWEEN CONTACTING AREAS OF SUCH COATED PAPER BLANK AND TOREDUCE CHATTERING AND FRICTIONAL RESISTANCE BETWEEN SAID COATED PAPERBLANK AND MACHINERY FOR HANDLING SUCH PAPER BLANK.